Norwegian Rolling B.ock

I have a Norwegian Rolling Block, date stamped 1877. It is not a 50-70 gov. the bore at the muzzle is 12.03 mm or 0.485 ". The groove diameter at the muzzle is 13.06 mm or 0.497 ". What caliber is this? Are bullets in this size available anywhere? How about reloading dies? The 50-70 gov case fits the chamber. Confused.

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Originally Posted by ydouask

I have a Norwegian Rolling Block, date stamped 1877. It is not a 50-70 gov. the bore at the muzzle is 12.03 mm or 0.485 ". The groove diameter at the muzzle is 13.06 mm or 0.497 ". What caliber is this? Are bullets in this size available anywhere? How about reloading dies? The 50-70 gov case fits the chamber. Confused.

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I have one too. I use .348 Win brass with the rim turned down, expanded to 50 cal and trimmed to length or 50-70 brass with the rims turned. I use commercial cast bullets 0.502" diameter or muzzle loader REAL bullets I cast myself. I use black powder or subs. I believe the official Norwegian caliber was 12.7 x 44R.

If you are using a metric micrometer you need to check your math.

12.03 mm converts to 0.4736" and 13.06 mm converts to 0.5141"

Tim

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Originally Posted by dtknowles

I have one too. I use .348 Win brass with the rim turned down, expanded to 50 cal and trimmed to length or 50-70 brass with the rims turned. I use commercial cast bullets 0.502" diameter or muzzle loader REAL bullets I cast myself. I use black powder or subs. I believe the official Norwegian caliber was 12.7 x 44R.

If you are using a metric micrometer you need to check your math.

12.03 mm converts to 0.4736" and 13.06 mm converts to 0.5141"

Tim

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Thank you for your response. Not only was my math incorrect but after doing several more readings at the muzzle I have an average of .476" or 12.11 mm on the lands , and an average of .506" or 12.84 mm at the grooves..... those numbers I will check again tomorrow. I suspect that the Norwegian " 50-70 gov " was 12.17 mm " x44R and the Swedish 50-70 was 12.7 mm x44R. This translates to the Norwegian bore being .479 " and the Swedish being .515 ". So, you're shooting .502 "... that will work. I sure wouldn't be able to shoot those in my rifle. Is there a commercial bullet in the .479 " or slightly smaller range? Hank.

I have one and load 12.7 x 44 mm. The bore I measured at 0.488"/0.506" and it has the deepest rifling I have ever seen. Cases can be made from 348 Winchester brass or better 450/400 Nitro cases. I use a Lyman 450gn boolit sized to 0.510". The bore on my rifle is perfect and mirrored.

N.B. a 50/70 case will not fit but several smiths have run a 50/70 reamer into the chamber !

https://i.imgur.com/aJWgwDdl.jpg

https://i.imgur.com/XyVVmgdl.jpg

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Originally Posted by ydouask

Thank you for your response. Not only was my math incorrect but after doing several more readings at the muzzle I have an average of .476" or 12.11 mm on the lands , and an average of .506" or 12.84 mm at the grooves..... those numbers I will check again tomorrow. I suspect that the Norwegian " 50-70 gov " was 12.17 mm " x44R and the Swedish 50-70 was 12.7 mm x44R. This translates to the Norwegian bore being .479 " and the Swedish being .515 ". So, you're shooting .502 "... that will work. I sure wouldn't be able to shoot those in my rifle. Is there a commercial bullet in the .479 " or slightly smaller range? Hank.

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I think you would be better off shooting a bullet closer to groove diameter than bore diameter.

Tim